Evaluating the impact of a cemetery on groundwater by multivariate analysis

Water analyses in conjunction with hydrological and geotechnical investigations were carried out to assess the potential for groundwater contamination from the decomposition of buried human bodies. Water samples were collected from 2007 to 2018 in three monitoring wells built within the cemetery area. Water quality was evaluated based on the determination of 25 analytical parameters (20 physical-chemical and 5 microbiological). Laboratory data reported by the local sewage water company for water collected in household cisterns located outside the cemetery area were also evaluated. Multivariate analysis showed a similar pattern between iron content, turbidity, and rainfall data collected at the rainfall station closest to the study area. This behavior is a direct consequence of soil leaching (oxisol). The physical characterization of the soil of the unsaturated area above the aquifer indicates that the absorption of body waste by the soil is favored, preventing surface contaminants from reaching the aquifer. This work also found that the water samples collected outside the cemetery area do not comply with the Brazilian limits for drinking water. In conclusion, water samples collected from monitoring wells located within the cemetery area have little to none impact on both subsurface and underground contamination.

Mycorrhizal fungi alleviate acidification-induced phosphorus limitation: Evidence from a decade-long field experiment of simulated acid deposition in a tropical forest in south China

South China has been experiencing very high rate of acid deposition and severe soil acidification in recent decades, which has been proposed to exacerbate the regional ecosystem phosphorus (P) limitation. We conducted a 10-year field experiment of simulated acid deposition to examine how acidification impacts seasonal changes of different soil P fractions in a tropical forest with highly acidic soils in south China. As expected, acid addition significantly increased occluded P pool but reduced the other more labile P pools in the dry season. In the wet season, however, acid addition did not change microbial P, soluble P and labile organic P pools. Acid addition significantly increased exchangeable Al³⁺ and Fe³⁺ and the activation of Fe oxides in both seasons. Different from the decline of microbial abundance in the dry season, acid addition increased ectomycorrhizal fungi and its ratio to arbuscular mycorrhiza fungi in the wet season, which significantly stimulated phosphomonoesterase activities and likely promoted the dissolution of occluded P. Our results suggest that, even in already highly acidic soils, the acidification-induced P limitation could be alleviated by stimulating ectomycorrhizal fungi and phosphomonoesterase activities. The differential responses and microbial controls of seasonal soil P transformation revealed here should be implemented into ecosystem biogeochemical model for predicting plant productivity under future acid deposition scenarios.

Industrial saline wastewater in a corn-soybean rotation to enhance crop yield without compromising soil health in a subtropical soil

The production of industrial waste has increased in the last decades along with world population. Wastes are used in agriculture as fertilizers and soil amendments depending on their composition, dynamics in soil and effects on plant growth. The aim of this study was to assess the effect of industrial saline wastewater from heparin production on soil chemistry and plant yield in a subtropical soil in Brazil. Five rates of industrial saline wastewater (0, 10, 20, 40 and 60 m3 ha-1 year-1) were applied as fertilizer in a corn -soybean rotation on an Oxisol with limited nutrient availability. Five soils sampling were done: before and after the first application of the industrial wastewater (2017, corn), before and after the second application of wastewater (2018, soybean) and two years after the first application (2019). Soil K, Ca, Mg, Na content and CEC increased immediately after the application of wastewater but they returned to former values with time due to plant uptake and lixiviation. Wastewater application significantly increased corn (all rates) and soybean (only with the highest rate) yields around 103-250% and 50%, respectively, in comparison with no wastewater application. However, the highest rate temporally increased soil Na content and electrical conductivity (up to 650 and 800%, respectively). Although nutrient uptake, chlorophyll content and corn and soybean yields were enhanced, the use of high rates of industrial saline wastewater could cause soil salinization (mainly in locations with low rainfall), affecting soil chemistry and physical parameters due to clay dispersion, and pollution or water bodies.

Effect of ferrolysis and organic matter accumulation on chromate adsorption characteristics of an Oxisol-derived paddy soil

How paddy cultivation influences the adsorption isotherms, envelopes, and the kinetics of hexavalent chromate (Cr(VI)) on Fe (hydro)oxide-rich paddy soil, as well as the mechanisms involved, remain largely unaddressed. To this end, the Cr(VI) adsorption characteristics on a paddy soil, in comparison with its parent upland Oxisol, were studied. The results showed that Cr(VI) adsorption capacities (Q_m^ad) were higher in the surface Oxisol than in the same layer of paddy soil. The Q_m^ad increased by 18.0% and 41.3% after removal of soil organic matter (SOM) from the surface Oxisol and paddy soil layers, respectively, indicating that Cr(VI) adsorption was considerably inhibited by SOM. The adsorption and desorption isotherms demonstrated that non-electrostatic adsorption was mainly responsible for Cr(VI) adsorption, accounting for 59.37%-83.42% of Cr(VI) adsorption capacities. The negative shift of the zeta potential-pH curves with Cr(VI) loading further corroborated the finding that non-electrostatic adsorption is largely responsible for Cr(VI) retention. Cr(VI) adsorption at equilibrium, obtained by the stirred flow chamber technique, and the free Fe (hydro)oxides (Fe_d) contents were in the same order, suggesting that Fe_d are the main adsorbents for Cr(VI). Therefore, paddy cultivation has had a profound impact on the electrochemical properties of the Oxisol and on subsequent Cr(VI) adsorption characteristics.

A New Approach to UV Protection by Direct Surface Functionalization of TiO2 with the Antioxidant Polyphenol Dihydroxyphenyl Benzimidazole Carboxylic Acid

Skin cancer is the most common malignant cancer with an incidence of 1 million cases/year. It is well known that exposure to UV radiation from sunlight leads the most frequent risk factors for several skin disorders including skin cancer. Sunscreen filters represent a valid protection against dangerous effects derived from UV radiation, and they can be divided in organic and inorganic UV filters. Adding, at the product formulation, molecules with booster effect, or also substances that can increase the protecting effectiveness via synergic mechanisms, can further enhance their protection activity. Moreover, this approach leads to develop formulations with high SPF (Sun Protection Factor) with a reduced content of UV filters, this is in line with the recent decisions of yet a few countries (Palau, Thailand, Philippines, and Hawaii) to ban some sunscreen filters to preserve marine environments (i.e., reef). In this work, a new class of sunscreen UV filters has been synthesized, by means the combination of physical filter and Oxisol, an antioxidant molecule with booster effect. In this study, the synthesis of new physical multifunctional ingredients is reported, by means the direct surface functionalization of inorganic filters (in particular TiO₂) with Oxisol. In this study, the full characterization of these multifunctional ingredients is also reported, in addition to the cytotoxicity tests, the photocatalytic activity and the rheological properties involved on skin application.

Potential of Grasses in Phytolith Production in Soils Contaminated with Cadmium

Cadmium (Cd) is a very toxic heavy metal occurring in places with anthropogenic activities, making it one of the most important environmental pollutants. Phytoremediation plants are used for recovery of metal-contaminated soils by their ability to absorb and tolerate high concentrations of heavy metals. This paper aims to evaluate the potential of grasses in phytolith production in soils contaminated with Cd. The experiments, separated by soil types (Typic Quartzipsamment, Xanthic Hapludox and Rhodic Hapludox), were conducted in a completely randomized design with a distribution of treatments in a 3 × 4 factorial scheme with three replications. The factors were three grasses (Urochloa decumbens, Urochloa brizantha andMegathyrsus maximus) and four concentrations of Cd applied in soils (0, 2, 4 and 12 mg kg⁻¹). Grass growth decreased and increased Cd concentration in shoots of grasses with the increased Cd rates in soils. The toxic effect of Cd resulted in production and Cd occlusion in phytoliths produced in shoots of the grasses. Grasses showed potential for phytolith production, independent of soil type, providing phytoextraction of Cd in phytoliths. Megathyrsus maximus was the grass with the highest tolerance to Cd, evidenced by higher production and Cd capture in phytoliths for the evaluated soils. Phytolith production by grasses in Cd-contaminated soils is related to genetic and physiological differences of the evaluated grasses and Cd availability in soils.

Synthesis and Characterization of New Multifunctional Self-Boosted Filters for UV Protection: ZnO Complex with Dihydroxyphenyl Benzimidazole Carboxylic Acid

The incidence of skin cancer is increasing both because of climate change and the increase in pollution than people’s incorrect habits of sun exposure. In these regards, sunscreen and photoprotection are essential tools in consenting the benefits induced by safe solar light exposition and skin cancer prevention. In this work, a new class of sunscreen filter was synthesized by chemical combination of a physical filter (ZnO) and Oxisol (dihydroxyphenyl benzimidazole carboxylic acid), an antioxidant molecule with booster effect. In this work, a new class of filters with new properties was achieved by direct functionalization of particles surface. A full characterization of this multifunctional ingredient (ZnO–Ox) was conducted: Compared with the simple mixture, the new filter acts as a multifunctional molecule showing a higher Sun Protection Factor (SPF), a better cytotoxic profile (MTT and NRU assay), and anti-acne activity. A strong reduction of photocatalytic activity of ZnO was observed, also improving the safety profile.

Macroaggregation and soil organic carbon restoration in a highly weathered Brazilian Oxisol after two decades under no-till

Conclusions based on studies of the impacts of soil organic carbon (SOC) fractions and soil texture on macroaggregation and SOC stabilization in long-term (>20years) no-till (NT) fields remain debatable. This study was based on the hypothesis that the amount and frequency of biomass-C input associated with NT can be a pathway to formation of macroaggregates and to SOC buildup. The objectives were to: 1) assess the macroaggregate distribution (proportional mass, class mass) and the SOC and particulate organic carbon (POC) stocks of extra-large (8-19mm), large (2-8mm) and small (0.25-2mm) macroaggregate size classes managed for two decades by NT, and 2) assess the recovery of SOC stocks in extra-large macroaggregates compared to adjacent native vegetation (Andropogon sp., Aristida sp., Paspalum sp., and Panicum sp.). The crop rotation systems were: soybean (Glycine max L.), maize (Zea mays L.) and beans (Phaseolus vulgaris L.) in summer; and black oat (Avena strigosa Schreb), white oat (Avena sativa), vetch (Vicia sativa L.), black oat.+vetch (Avena strigosa Schreb+vetch) and wheat (Triticum aestivum L.) in winter. The experimental was laid out as 2×2 randomized block factorial with 12 replicates of a NT experiment established in 1997 on two highly weathered Oxisols. The factors comprised of: (a) two soil textural types: clay loam and sandy clay, and (b) two sampling depths: 0-5 and 5-20cm. The three classes of macroaggregates were obtained by wet sieving, and the SOC content was determined by the dry combustion method. The extra-large macroaggregate classes in 0-20cm depth for sandy clay (SdC) and clay loam (CL) Oxisol represented 75.2 and 72.4% of proportional mass, respectively. The SOC and POC stocks among macroaggregate classes in 0-5 and 5-20cm depths decreased in the order: 8-19mm>2-8mm ≈ 0.25-2mm. The SdC plots under soybean/maize at 3:1 ratio recovered 58.3%, while those at 1:1 ratio (high maize frequency) in CL recovered 73.1% of SOC stock in the extra-large macroaggregates compared with the same under native vegetation for 0-20cm depth. Thus, partial restoration of the SOC stock in original extra-large macroaggregate confirms the hypothesis that NT through higher maize cultivation frequency can be a pathway to fomation of macroaggregates and SOC buildup.

Evaluation of ferrolysis in arsenate adsorption on the paddy soil derived from an Oxisol

Iron oxides are dominant effective adsorbents for arsenate in iron oxide-rich variable charge soils. Oxisol-derived paddy soils undergo intensive ferrolysis, which results in high leaching and transformation of iron oxides. However, little information is available concerning the effect of ferrolysis on arsenate adsorption by paddy soil and parent Oxisol. In the present study, we examined the arsenate affinity of soils using arsenate adsorption/desorption isotherms, zeta potential, adsorption kinetics, pH effect and phosphate competition experiments. Results showed that ferrolysis in an alternating flooding-drying Oxisol-derived paddy soil resulted in a significant decrease of free iron oxides and increase of amorphous iron oxides in the surface and subsurface layers. There were more reactive sites exposed on amorphous than on crystalline iron oxides. Therefore, disproportionate ratios of arsenate adsorption capacities and contents of free iron oxides were observed in the studied Oxisols compared with paddy soils. The Gibbs free energy values corroborated that both electrostatic and non-electrostatic adsorption mechanisms contributed to the arsenate adsorption by bulk soils, and the kinetic adsorption data further suggested that the rate-limiting step was chemisorption. The zeta potential of soil colloids decreased after arsenate was adsorbed on the surfaces, forming inner-sphere complexes and thus transferring their negative charges to the soil particle surfaces. The adsorption/desorption isotherms showed that non-electrostatic adsorption was the main mechanism responsible for arsenate binding to the Oxisol and derived paddy soils, representing 91.42-94.65% of the adsorption capacities. Further studies revealed that arsenate adsorption was greatly inhibited by increasing suspension pH and incorporation of phosphate.

Ecotoxicological characterization of sugarcane vinasses when applied to tropical soils

The impact of sugarcane vinasse on soil invertebrates was assessed through ecotoxicological assays. Increasing concentrations of two vinasses from different distillery plants (VA and VB), and a vinasse from a laboratory production (VC), were amended on two natural tropical Oxisols (LV and LVA) and a tropical artificial soil (TAS) to characterize the effects of the vinasses on earthworms (Eisenia andrei), enchytraeids (Enchytraeus crypticus), mites (Hypoaspis aculeifer) and collembolans (Folsomia candida). The highest concentrations of VA and VB were avoided by earthworms in all soils and by collembolans especially in the natural soils. The presence of VC in all of the tested soils did not cause avoidance behavior in these species. The reproduction of earthworms, enchytraeids and collembolans was decreased in the highest concentrations of VA and VB in the natural soils. In TAS, VB reduced the reproduction of all test species, whereas VA was toxic exclusively to E. andrei and E. crypticus. The vinasse VC only reduced the number of earthworms in TAS and enchytraeids in LVA. The reproduction of mites was reduced by VB in TAS. Vinasses from distillery plants were more toxic than the vinasse produced in laboratory. The vinasse toxicities were influenced by soil type, although this result was most likely because of the way the organisms are exposed to the contaminants in the soils. Toxicity was attributed to the vinasses' high salt content and especially the high potassium concentrations. Data obtained in this study highlights the potential risk of vinasse disposal on tropical soils to soil biota. The toxic values estimated are even more relevant when considering the usual continuous use of vinasses in crop productions.